Control mechanism for sewing machine

ABSTRACT

This disclosure relates to a control mechanism for a blindstitch tacker wherein a single control device is provided for progressively moving a node former and work clamp of a sewing machine into clamping engagement with a workpiece, and further movement of the control mechanism results in the initiation of the stitching operation. The control mechanism includes a multiple lever arm bell crank with different ones of the lever arms thereof actuating different mechanisms of the sewing machine. The control mechanism also includes a cam and cam follower for actuating the node former and work clamp with there being an overcenter position wherein further movement of the bell crank does not result in further movement of the node former and work clamp. When the bell crank has moved to this position, a spring retains the bell crank in its operative position without assistance by the operator. The control mechanism is automatically returned to its inoperative position upon the termination of a predetermined sewing cycle.

United States Patent Hsiao [451 Sept. 26, 1972 [54] CONTROL MECHANISM FOR SEWING MACHINE [72] Inventor: James C. l-lsiao, Chicago, lll.

' [73] Assignee: Union Special Machine Company,

Chicago, Ill.

[22] Filed: April 30, 1971 [21] Appl. No.: 138,979

[52] U.S.Cl ..ll2/176, 112/67 Primary ExaminerH. Hampton Hunter Attorney-Diner, Brown, Ramik & Holt [57] ABSTRACT This disclosure relates to a control mechanism for a blindstitch tacker wherein a single control device is provided for progressively moving a node former and work clamp of a sewing machine into clamping engagement with a workpiece, and further movement of the control mechanism results in the initiation of the stitching operation. The control mechanism includes a multiple lever arm bell crank with different ones of the lever arms thereof actuating different mechanisms of the sewing machine. The control mechanism also includes a cam and cam follower for actuating the node former and work clamp with there being an overcenter position wherein further movement of the bell crank does not result in further movement of the node former and work clamp. When the bell crank has moved to this position, a spring retains the bell crank in its operative position without assistance by the operator. The control mechanism is automatically returned to its inoperative position upon the termination of a predetermined sewing cycle.

16 Claims, 4 Drawing Figures PAIENTED SEP 26 1972 SHEEI 1 0F 2 \NVENTUR JAMES C. HS\AD HTTURNECS PATENTEDSEPZS I972 SHEET 2 [IF 2 w s m W WW o s M E A Q w 5 mg w I m, 0. O 0 m s Q N. mam

CONTROL MECHANISM FOR SEWING MACHINE This invention relates in general to new and useful improvements in sewing machines, and more particularly to a control mechanism for a blindstitch tacker.

BACKGROUND OF THE INVENTION Blindstitch tackers and other sewing machines particularly constructed to form predetermined groups of stitches are well known. The patent to Charles W.

.Mueller, et. al. U.S. Pat. No. 2,889,793granted June 9,

1959, discloses such a sewing machine construction. Further, additional details of such a sewing machine construction are found in the patent to Nelson, U.S. Pat. No. 2,609,773 referred to in the Mueller, et. al. patent.

The Mueller, et al. patent discloses a blindstitch tacker which includes a node former and work clamp which is positioned by an operator depressing a foot treadle and moving acontrol lever therefor. The sewing machine of the Mueller, et al. patent also discloses a stop motion control mechanism which is provided with an independent control lever and operated by means of a second treadle.

It will be readily appreciated that with the Mueller, et al. arrangement, it is necessary for the operator to perform two separate and independent control actions with different parts of the operators body, such as with the operators two feet acting independently. This, of course, permits the possibility of confusion.

The patent to Althens, U.S. Pat. No. 2,385,768, granted Oct. 2, I945, discloses a conventional sewing machine which requires two separate operations on the part of the machine operator, the first operation being controlled by a foot treadle 58 for effecting the clamping of the workpiece to be sewn, and the second operation requiring the depressing of a foot treadle 87 in order to release the stop motion mechanism of the sewing machine.

It is also known in the sewing machine art to provide a single actuator for two different control devices. This is shown in the patent to Hayes U.S. Pat. No. 2,540,730 granted Feb. 6, 1951. However, the two separate control devices are merely connected together by an equalizing bar and other specific linkage is provided so as to provide the sequential operation.

SUMMARY OF THE INVENTION In accordance with this invention, it is proposed to provide a conventional sewing machine with a control mechanism which will permit the use of a single control device to sequentially actuate two known actuating mechanisms of such a sewing machine. The control device, upon an initial movement thereof, will effect the actuation of a first mechanism, and upon further movement thereof, will actuate the second sewing machine mechanism.

A principal feature of the control mechanism is the provision of a multiple lever arm bell crank wherein one lever arm is utilized to effect the operator controlled pivoting of the bell crank and two other lever arms are utilized to independently control the movement of two separate actuating mechanisms of the sewing machine.

tuating mechanism which is first to be actuated by means of a cam and cam follower arrangement which has associated therewith an overcenter arrangement whereby once this portion of the sewing machine has been actuated, further movement of the bell crank will not result in further actuation thereof, thereby permitting the bell crank to be moved further to effect the sequential actuation of the second mechanism.

Another feature of the overcenter cam and cam follower relationship is that an interlock may be obtained between levers of the control mechanism so as to lock the bell crank in its fully actuated position, thereby permitting the control mechanism to be released by the machine operator. Associated with this is a spring for holding the cam follower in its overcenter position by reacting on levers of the control mechanism in opposite directions.

The control mechanism is further constructed wherein after a predetermined stitching sequence has been performed, a stop motion mechanism of the sewing machine will be reset and in the resetting of the stop motion mechanism, the control mechanism will be returned to its normal inoperative position independently of any function on the part of the machine operator.

The control mechanism is particularly adapted for incorporation in a blindstitch tacker, but may be utilized in conjunction with any type of sewing machine which requires two separate operations on the part of the operator and is particularly adapted for use in conjunction with sewing machines which are programmed to form a predetermined number of stitches upon each actuation thereof.

-With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

In the drawings:

FIG. 1 is a rear elevational view of the sewing machine with parts broken away and showing the control mechanism in its operative position.

FIG. 2 is a rear elevational view similar to FIG. 1 but with the control mechanism in its operative position.

FIG. 3 is a side elevational view of the sewing machine with parts broken away and shown in section and showing the connection between the control mechanism and sewing machine mechanism.

FIG. 4 is a vertical sectional vieyv taken along the line 4-4 of FIG. 3 and shows further the details of the sewing machine.

Referring now to the drawings in detail, it will be seen that there is illustrated a sewing machine of the general type disclosed in the patent to Charles W. Mueller, et. al. U.S. Pat. No. 2,889,793. This sewing machine discloses a base 6 which is normally secured to a table board (not show). Above and conventionally hinged to the base 6 by means of a hinge 7 is the frame of the sewing machine, the frame being generally identified by the numeral 8. The frame 8, as is best shown in FIG. 3, includes a section 9 that directly rests on the base 6 and has a horizontal arm 10 extending therefrom. An upright post 11 is secured to the section 9 and, in turn, supports a horizontal arm 12 which extends from the upper end of the post 11. Remote from the post 11, the arm 12 carries a needle head 13 which extends downwardly towards the arm 10.

The needle head 13 is of a conventional type and the lower portion thereof is provided with a needle arm 14 whichcarries a needle 15. The needle head 13 also supports a rotary looper 16 which cooperates with the needle to form stitches. The needle head 13 also carries a presser foot 17 which is disposed below the needle 15 and the looper 16.

. Below and in spaced relationship to the presser foot 17 is a circular work support plate 18. The work support plate 18 is rigidly'securecl to the arm 10 in a conventional manner. In the center of the work support plate 18 there is provided a hole 20 through which a node former 21 and a work clamp 22 are able to pass. The hole 20 is larger in diameter than the work clamp 22 so that the work clamp is allowed free movement.

In FIG. 3, the work clamp 22 and the node former 21 are illustrated in their down or inoperative position. In this position the top surface of the work clamp and node former lie in substantially the same plane as the top surface of the work support plate 18.

It is to be noted that the work clamp 22 is slidably mounted on a shaft portion 23 of the node former 21 with a spring 24 surrounding the shaft portion 23 and biasing the work clamp 22 upwardly. Upward movement of the work clamp 22 relative to the node former 21 is limited by engagement of a shoulder on the work clamp against an under shoulder on the node former at The shaft portion 23 is slidably mounted in a node former frame 26 and has a reduced shaft portion 27 which passes out through the bottom of the node former frame 26. Stop nuts 28 are threadedly engaged on the exposed end of the of the shaft portion 27 and restrict the upward movement of the node former 21 relative to the node former frame 26. The node former 21 is biased upwardly by a spring 30 disposed around the shaft portion 27 and reacting against the lower end of the shaft portion 23 and a shoulder defined by the base of a cylindrical recess 31 in the node former frame 26 in which the shaft portion 23 is slidably mounted.

The node former frame 26 includes a barrel portion 32 which is slidably mounted in a node former bearing block 33. The node former frame, which carries the node fonner and the work clamp, is movable up and down in the node former bearing block by means of a link 34 which is pivotally connected at one of its ends to the node former frame and at its other end to a node former crank 35 by means of shoulder screws 36. The node former crank 35 is adjustably secured to a node former shaft 37 for oscillation therewith. It is to be understood that the specific details of the adjustable connection between the node former crank 35 and the shaft 37 are not a part of this invention and therefore, are not described in detail although they differ somewhat from that disclosed in the aforementioned Mueller, et. al. patent.

The node former shaft 37 is suitably mounted at one end in bearings 38 and 40 carried by the machine frame. The opposite end of the shaft 37 is suitably mounted in a bearing (not shown) carried by the node former bearing block 33. The bearing block 33 is suitably rigidly secured to the arm 10 by means of screws or other fasteners in a manner not illustrated here in that it forms no part of this invention.

Manual oscillation of the shaft 37 is obtained through a shaft 41 which is suitably journalled in bearings carried by the section 9 of the machine frame. One end of the shaft 41 extends through and beyond the rear wall of the section 9 and on this extended end of the shaft 41 there is secured a lever 42. The lever 42 is operatively connected to suitable actuating means which are parts of this invention and which will be described in more detail hereinafter.

An arm 43 is secured to the shaft 41 and is connected by means of a link 44 to one arm 45 of a lever 46. The lever 46 is, in turn, secured to the shaft 37 for effecting the oscillation thereof. The lever 46 includes a further arm 47 which engages the hub of the arm 43 and functions as a stop for the purpose of stopping the node former in the correct up position thereof so as to present a ridge of the work up through a slot (not shown) in the presser foot 17 and into the path of the needle 15.

Referring now to FIG. 1, it will be seen that the lever 42 is operatively connected with a lever 48. The lower portion of the lever 48 is provided with an opening 50 of which a portion thereof is defined by a cam surface 51 which terminates in a restricted portion 52 of the opening 50. The free end of the lever 42 is provided with a cam follower 53 which is disposed within the opening 50 and which is in engagement with the cam surface 5]. It is also to be noted that the cam follower 53 is of a diameter to be received within a restricted opening portion 52 with there being a minimum of play.

The lever 48 is one arm of a bell crank generally identified by the numeral 54 and includes a hub 55 which is freely pivotable on a shaft 56 which is carried by the upright post 11 and extends therebeyond. The bell crank 54 also includes a lever arm 57 which extends to the right of the pivot point for the bell crank 54, as viewed in FIG. 1. The lever arm 57 has a chain 58 connected thereto with the chain 58 depending therefrom. The other end of the chain 58 is connected in a conventional manner to a foot treadle (not shown) or other suitable actuating means.

A spring 60 is connected at one end to the lever arm 57 and at its opposite end to a lever arm 61 which is integrally connected with the lever 42 and together therewith to form a bell crank 62. The spring 60 constantly urges the bell crank 54 in a clockwise direction and the ball crank 62 in a counterclockwise direction thereby maintaining contact between the cam follower 53 and the cam surface 51.

The bell crank 54 includes a third lever arm 63 which terminates in a right angle portion 64. The right angle portion 64 has adjustably threadedly engaged therein an adjustable stud 65 which is locked in an adjusted position by means of a lock nut 66. When the bell crank 54 is pivoted in a clockwise direction by the downward movement of the chain 58, the stud 65 will engage a stop motion lever 67 and pivot the same in a clockwise direction to a released position. The stop motion mechanism will not be discussed in detail here in that the specific details thereof are not a part of this invention. It is to be understood, however, that the mechanism will be comparable to that shown in the Mueller, et al. U.S. Pat. No. 2,889,793 and more specifically disclosed in the patent to Nelson, U.S. Pat. No. 2,609,773 referred to therein.

When the lever arm 57 is moved downwardly by the downward movement of the chain 58, the lever arm 48 will swing in a clockwise direction with the result that the lever arm 42 will be moved likewise in a clockwise direction by the reaction of the cam surface 51 on the cam follower 53. The shaft 41 will be rotated by the limited rotation of the bell crank 62 and through the links 43, 44 and 45, the shaft 37 will also be rotated through a predetermined arc. This will effect the clamping of the work against the bottom of the presser foot 17 by the upward moving work clamp 22. With the work fully clamped, the operator will cause further downward movement of the chain 58 in a second step. At this time the cam follower 53 will run off of the cam surface 51 and into the narrow opening 52 to the position shown in FIG. 2. This will bring the bell cranks 54 and 62 to the position shown in FIG. 2.

With particular reference to FIG. 2 it will be seen that the stop motion lever 67 will have been pivoted a limited amount in a clockwise direction and a stop element 68 thereof will be released from abutment with a shoulder 70 of a pulley 71 which is secured to a mainshaft 72 of the sewing machine. When the stop motion lever 67 is released from the pulley 71, a conventional clutch (not shown) in the pulley 71 will be engaged and the sewing machine will start its sewing cycle. The operator can now release the chain 58 because the bell cranks 54 and 62 will remain locked in position by the tension of the spring 60 and the seating of the cam follower 53 into the narrow opening portion 52. It is understood that the material will be kept clamped in the desired position throughout the sewing cycle.

The length of the sewing cycle is determined by a conventional stitch cam arrangement 73. The cam 73 is secured to a shaft 74 which is mounted for rotary motion in suitable hearings in the machine frame. The cam 73 is provided with three sets of notches which determine the number of stitches of the sewing cycle. It is to be understood that the stitch setting can be changed by a stitch adjusting lever 75 which is fixed to the shaft 56. It is to be understood that the stitch adjusting mechanism in of itself is not a part of this invention and is fully explained in the aforementioned Mueller, et al. US. Pat. No. 2,889,793.

Although the stitch adjusting mechanism is more fully explained in the Mueller, et al. patent, the manner in which the different sewing cycles may be obtained will be pointed out here. A gear ratio of 24:1 is accomplished by a worm 76 fixed to the main shaft 72 and cooperating with a worm gear 77 fixed to a traverse shaft 78; A further gear 80, also fixed to the traverse shaft 78, meshes with a gear 81 fixed to the shaft with the end result being that for every twenty four revolutions of the main shaft 72, the cam 73 will revolve only once. The cam 73 is provided with three different sets of notches, one set of notches including two notches for the purpose of forming 12 stitches during a sewing cycle: another set of notches including three notches for forming eight stitches during a sewing cycle: and the third set of notches including four notches for forming six stitches during a sewing cycle.

In FIG..4, it can be seen that the stitch adjusting lever 75 has an upstanding arm portion 82 which carries a cam follower 83. When the sewing machine is in its inoperative position, the cam follower 83 rests in one of the notches or depressions of the cam 73. When the chain 58is tensioned fully to start the operation of the sewing machine, the cam follower 83 is lifted out of the respective notch in the cam 73 and then rides on the surface of the cam 73 as the cam rotates during the operation of the sewing machine. When the cam follower 83 reaches the next notch, it drops into the notch followed by a resultant rocking of the shaft 56.

The cam follower 83 is constantly biased towards the cam 73 by a spring 84 which has one end thereof anchored on a pin 85 projecting from the machine frame and the other end thereof engaged with the stop motion lever 67. When the cam follower 83 enters into one of the notches in the cam 73, the shaft 56 is rotated in a counterclockwise direction as viewed in FIGS. 1, 2 and 4 with the result that the stop motion lever 67 also moves in a counterclockwise direction with the stop element 68 thereof engaging the pulley 71 and stopping rotation of the main shaft 72. Movement of the stop motion lever 67 in a counterclockwise direction will also result in rotation of the bell crank 54 in a counterclockwise direction sufficiently for the cam follower 53 to move out of the narrow opening portion 52 to a position wherein the lever arms 42 and 48 are no longer interlocked and wherein the spring 60 will now cause the bell cranks 54 and 62 to return to their original positions.

With particular reference to FIG. 1, it will be seen that an adjustable stop 86 is provided in the machine frame for engagement with the lever arm 42 to limit the pivoting of the lever arm 42 in a counterclockwise direction due to the urging of the spring 60. In like manner, the coaction of the cam surface 51 with the cam follower 53 will limit the pivoting of the lever arm 48 in a clockwise direction due to the urging of the spring 60.

It is to be understood that when the bell cranks 54 and 62 are returned to their normal positions, not only will the work clamp 22 and the node former 21 be lowered to work releasing positions, but also the clutch (not shown) associated with the pulley 71 will be released. The sewing machine is now ready to receive another workpiece after the removal of the workpiece which hasjust been sewn.

It is further to be understood that the sewing machine may be equipped with a conventional thread wiper and a conventional thread cutter (not shown). With particular reference to FIG. 4, it will be seen that there is mounted within the upright post 11 a vertically extending link 87. The link 87 is provided at the upper end thereof with a vertically elongated slot 88 through which the main shaft 72 passes. The lower end of the link 87 is connected to an arm or lever 90 which is rigidly secured to the shaft 41. The link 87 has associated therewith control mechanisms 91 for the thread wiper and thread cutter which are actuated in response to vertical movement of the link 87. It is to be understood that the shaft 41 is oscillated by means of the bell crank 62 in positioning the node former 21 and the work clamp 22 and that simultaneous with the positioning of the node former and the work clamp, the link 87 is shifted so as to control the operation of the thread wiper and thread cutter.

It is to be understood that although the control mechanism has been specifically illustrated for use in conjunction with a 'blindstitch spot tacker, the invention is not limited to such a sewing machine installation, but may be used in conjunction with other types of group stitch machines. ltwill be readily recognized from the foregoing that the principal feature of the invention is the provision of a single operator controlled mechanism which has a first range of movement to effect the clamping of work in place for stitching, and a further range of movement for effecting the operation of the sewing machine to form the desired predetermined stitching.

Although only a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the control assembly without departing from the 'spiri t and scope of the invention as defined by the appended claims.

I claim:

1. In a sewing machine having first and second operator actuated controls, a single control mechanism for actuating said first and second controls in sequence, said control mechanism including first means for operation by an operator and second and third means operable in unison by and with said first means, first connecting means between said second means and said first control for actuating said first control during a first movement of said first means, and second connecting means between said third means and said second control for actuating said second control during a second movement of said first means and after the actuation of said first control.

2. The sewing machine of claim 1 wherein said first connecting means includes a lost motion connection operable only after said first control has been actuated for facilitating the actuation of said second control whereby said second control may be actuated without influencing the position of said first control.

3. The sewing machine of claim 2 wherein said second control includes a lost motion connection operable during at least the initial actuation of said first control.

4. The sewing machine of claim 2 together with interlock means interconnecting said first means and said first control for holding said first means in an actuated position after said first and second controls have been actuated.

5. The sewing machine of claim 4 wherein said sewing machine includes release mechanism operable in timed response to the actuation of said second control to over ride said interlock means and release said con trol mechanism.

6. The sewing machine of claim 5 wherein said first control is for a work support and said second control is for a stop motion mechanism.

7. The sewing machine of claim 2 wherein said sewing machine includes a rockable shaft and said first, second and third means including a multiple arm crank pivotally mounted on said shaft, said second control being fixedly secured to said shaft for rocking the same in response to the actuation of said second control, and a stitch number control member carried by said shaft.

8. The sewing machine of claim 7 wherein said stitch number control member is co ns antly resiliently urged toward a position returning said irst means to a normal inoperative position, and wherein said sewing machine includes a rotating cam resisting the movement of said stitch number control member due to said urging during a sewing cycle.

9. The sewing machine of claim 8 together with interlock means interconnecting said first means and said first control for holding said first means in an actuated position after said first and second controls have been actuated.

10. The sewing machine of claim 9 wherein said interlock means is resilient and said resilient urging of said stitch number control member is sufficient to overcome said interlock means and move said second and third means to normal positions wherein said first and second controls are in the normal positions thereof for the inoperative position of said sewing machine.

11. A group stitch sewing machine having a sequential control mechanism operated by single control means, said sewing machine including a work clamp and a machine control device, and said single control means including a multiple lever arm bell crank having an operator controlled lever arm and a pair of machine controlling lever arms, fist linkage connecting one of said machine controlling lever arms to said work clamp for moving said work clamp to a work clamping position upon initial movement of said operator controlled lever arm, and second linkage connecting the other of said machine controlling lever arms to said machine Control device for moving said machine control device to a machine operating position upon further movement of said operator controlled lever arm.

12. The sewing machine of claim 11 wherein said sewing machine is a blindstitch spot tacker and includes a node former associated with said work clamp for movement therewith to an operative position.

13. The sewing machine of claim 11 wherein said first linkage includes an actuating lever, and a cam and cam follower connection between said actuating lever and said one machine controlling lever arm.

14. The sewing machine of claim 13 wherein a cam follower receiving slot is disposed adjacent said cam surface for permitting further movement of said bell crank without changing the position of said work clamp.

15. The sewing machine of claim 14 wherein a spring interconnects said bell crank and said actuating lever and locks said cam follower in said slot to retain said bell crank in its operative position.

16. The sewing machine of claim 15 wherein said machine control device includes means for resetting said bell crank after the forming of a preselected number of stitches.

UNITED STA'IES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,693,564 Dated September 26, 1972 Inventor(s C. It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 42, read "operative" as --inoperative-- Column 4, line 48, read "ball" as bell Figure 4, the upstanding arm portion should read as 2 Signed and sealed this 19th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. I I C. MARSHALL DANN Commissioner of Patents Attesting Officer USCOMM-DC 60876-P69 =ORM PO-105O (10-69) i u.s. GOVERNMENT rnm'rlne omc: nu o-ace-su, 

1. In a sewing machine having first and second operator actuated controls, a single control mechanism for actuating said first and second controls in sequence, said control mechanism including first means for operation by an operator and second and third means operable in unison by and with said first means, first connecting means between said second means and said first control for actuating said first control during a first movement of said first means, and second connecting means between said third means and said second control for actuating said second control during a second movement of said first means and after the actuation of said first control.
 2. The sewing machine of claim 1 wherein said first connecting means includes a lost motion connection operable only after said first control has been actuated for facilitating the actuation of said second control whereby said second control may be actuated without influencing the position of said first control.
 3. The sewing machine of claim 2 wherein said second control includes a lost motion connection operable during at least the initial actuation of said first control.
 4. The sewing machine of claim 2 together with interlock means interconnecting said first means and said first control for holding said first means in an actuated position after said first and second controls have been actuated.
 5. The sewing machine of claim 4 wherein said sewing machine includes release mechanism operable in timed response to the actuation of saId second control to over ride said interlock means and release said control mechanism.
 6. The sewing machine of claim 5 wherein said first control is for a work support and said second control is for a stop motion mechanism.
 7. The sewing machine of claim 2 wherein said sewing machine includes a rockable shaft and said first, second and third means including a multiple arm crank pivotally mounted on said shaft, said second control being fixedly secured to said shaft for rocking the same in response to the actuation of said second control, and a stitch number control member carried by said shaft.
 8. The sewing machine of claim 7 wherein said stitch number control member is constantly resiliently urged toward a position returning said first means to a normal inoperative position, and wherein said sewing machine includes a rotating cam resisting the movement of said stitch number control member due to said urging during a sewing cycle.
 9. The sewing machine of claim 8 together with interlock means interconnecting said first means and said first control for holding said first means in an actuated position after said first and second controls have been actuated.
 10. The sewing machine of claim 9 wherein said interlock means is resilient and said resilient urging of said stitch number control member is sufficient to overcome said interlock means and move said second and third means to normal positions wherein said first and second controls are in the normal positions thereof for the inoperative position of said sewing machine.
 11. A group stitch sewing machine having a sequential control mechanism operated by single control means, said sewing machine including a work clamp and a machine control device, and said single control means including a multiple lever arm bell crank having an operator controlled lever arm and a pair of machine controlling lever arms, fist linkage connecting one of said machine controlling lever arms to said work clamp for moving said work clamp to a work clamping position upon initial movement of said operator controlled lever arm, and second linkage connecting the other of said machine controlling lever arms to said machine control device for moving said machine control device to a machine operating position upon further movement of said operator controlled lever arm.
 12. The sewing machine of claim 11 wherein said sewing machine is a blindstitch spot tacker and includes a node former associated with said work clamp for movement therewith to an operative position.
 13. The sewing machine of claim 11 wherein said first linkage includes an actuating lever, and a cam and cam follower connection between said actuating lever and said one machine controlling lever arm.
 14. The sewing machine of claim 13 wherein a cam follower receiving slot is disposed adjacent said cam surface for permitting further movement of said bell crank without changing the position of said work clamp.
 15. The sewing machine of claim 14 wherein a spring interconnects said bell crank and said actuating lever and locks said cam follower in said slot to retain said bell crank in its operative position.
 16. The sewing machine of claim 15 wherein said machine control device includes means for resetting said bell crank after the forming of a preselected number of stitches. 